Diamino Groups Research Articles

Highly efficient photosynthesis of hydrogen peroxide by a stable Zr(IV)-based MOF with a diamino-functionalized ligand.

Metal-organic frameworks (MOFs) have emerged as a promising class of materials for solar-driven hydrogen peroxide (H2O2) generation due to their porosity, large surface area and designable molecular building blocks; however, producing H2O2 from oxygen and water without sacrificial agents remains a major challenge. Herein, we have constructed two UiO-67-type MOFs, UiO-67-NH2 and UiO-67-(NH2)2, by a solvothermal method using 2-amino-4,4'-biphenyldicarboxylic acid and 2,2'-diamino-4,4'-biphenyldicarboxylic acid as ligands, respectively. A variety of photochemical measurements have shown that the introduction of diamino groups into UiO-67-(NH2)2 not only enhances its absorption ability for visible light, but also facilitates the separation of photogenerated electron/hole pairs. Consequently, compared to monoamino-functionalized UiO-67-NH2, UiO-67-(NH2)2 exhibits a 5.5 times higher H2O2 production rate in pure water for 1 h. A two-step one-electron oxygen reduction reaction pathway for photocatalytic H2O2 production was suggested based on a series of control experiments and active species trapping tests by electron paramagnetic resonance spectra. This work provides new insights into the regulation of functionalized MOF ligands at the molecular level and a catalytic mechanism towards MOF-based photocatalysts for H2O2 production with high activity.

Gasotransmitter nitric oxide imaging in Alzheimer's disease and glioblastoma with diamino-cyclic-metalloiridium phosphorescence probes

Nitric Oxide (NO), a significant gasotransmitter in biological systems, plays a crucial role in neurological diseases and cancer. Currently, there is a lack of effective methods for rapidly and sensitively identifying NO and elucidating its relationship with neurological diseases. Novel diamino-cyclic-metalloiridium phosphorescence probes, Ir-CDA and Ir-BDA, have been designed to visualize the gasotransmitter NO in Alzheimer's disease (AD) and glioblastoma (GBM). Ir-CDA and Ir-BDA utilize iridium (III) as the central ion and incorporate a diamino group as a ligand. The interaction between the diamino structure and NO leads to the formation of a three-nitrogen five-membered ring structure, which opens up phosphorescence. The two probes can selectively bind to NO and offer low detection limits. Additionally, Ir-BDA/Ir-CDA can image NO in brain cancer cell models, neuroinflammatory models, and AD cell models. Furthermore, the NO content in fresh brain sections from AD mice was considerably higher than that in wild-type (WT) mice. Consequently, it is plausible that NO is generated in significant quantities around cells hosting larger Aβ deposits, gradually diffusing throughout the entire brain region. Furthermore, we posit that this phenomenon is a key factor contributing to the higher brain NO content in AD mice compared to that in WT mice. This discovery offers novel insights into the diagnosis and treatment of AD.

An MD-based physical characteristics analysis on the PI/EP duo-layer composites, impacting of diamino groups

Owing to the possible interfacial mismatching, the insulation performance in the polyimide-Epoxy (PI-EP) dual-layer composite structures would be reduced. In this paper, molecular dynamics simulations are used to study changes in various key physical characteristics of PI-EP composites agented by diamino groups, as well as the in-depth mechanisms. Particularly, the thermal-dynamics and dielectric characteristics were analyzed. Results indicated that agented by 4,4′-Diaminodiphenyl sulfur (SDA), the glass transition temperature was increased by 5 %, coefficient of thermal conductivity was increased by 18 %, and dielectric permittivity was reduced by 6 %. In addition, the density functional theory based calculations were applied to clarify the effects of diamino groups on the physical characteristics of the duo-layer composite structures, in the scope of electronics and energies. Agented by SDA, the duo-layer PI-EP composite is more suitable for the solid insulation of power electronics transformers.

Total synthesis of (–)-negamycin from a chiral advanced epoxide

A concise route for the total synthesis of (–)-negamycin is described. Key point features (a) Cu-mediated ring-opening reaction of the advanced epoxide with vinyl magnesium chloride leads to the introduction of the carboxyl synthon; (b) Consecutive placement of diamino groups via azides was designed, including an unexpected cleavage of the silyl protecting group; (c) removal of four hydrogenolytically labile groups in one step.

Synthesis and characterization of binary compounds of the novel Azetidin-2-one ring and comparison of its biological activity

New organic compounds were prepared with two groups of azetidine-2-one, respectively.And that through the first two steps: New compounds were prepared with two groups of azomethine, by reacting benzaldehyde derivatives with primary amino compounds with di-amino groups. The result was diagnosed by following TLC, M.P, FT.IR.The second step: The azomethine compounds prepared in the previous step reacted with acetic acid dichloride with different molar numbers (1:2) and were diagnosed spectroscopically and physically by (TLC, M.P, FT.IR,H1NMR,C13.NMR.C.H.N.X.) to confirm the correctness of the structural formula of the resulting compounds. Finally, the effect of these prepared compounds on types of gram-positive and gram-negative bacteria (Escherichia Coli, Klebsiella pneumoniae, Staphylococcus aureus P.aeruginosa.) was studied and the results were compared with types of drugs available in pharmacies (Cefotaxime (C.C.X 10) 5 mg/ disc, Chloramphenicol (C.C.30) 30mg/ disc, Cefixime (C.F.M5) 10mg/ disc, Amoxicillin (A.M.C30) 30 mg/ disc). The results were very satisfactory against the growth of types of bacteria, and the reason was due to the increase in the number of azetidine-2-one rings, meaning the greater the number of these rings, the greater the killing of bacteria.

Anchoring Highly Sulfonated Hyperbranched PBI onto oPBI: Fast Proton Conduction with Low Leaching

To achieve fast proton conduction with low leaching of the proton conductor, hyperbranched polybenzimidazole with abundant terminal diamino groups was synthesized and highly sulfonated to yield the cross-linkable proton conductor SHBPBI. A high-temperature proton exchange membrane (HTPEM) was prepared with ether containing polybenzimidazole (oPBI) and triallyl isocyanurate (TAIC). TAIC formed covalent bonds with N–H bonds in oPBI and SHBPBI, and effectively anchored soluble SHBPBI onto the oPBI-TAIC network without sacrificing proton-conducting sulfonic acid groups. oPBI-TAIC-SHBPBI exhibited good thermal stability, mechanical property, dimensional stability, oxidative resistance, membrane selectivity, and low methanol/H2/O2 crossover. The proton conductivity of oPBI-TAIC(5%)-SHBPBI(50%) achieved was 0.147, 0.074, and 0.034 S cm–1 at 100%, 50%, and 0 RH at 180 °C, respectively. The conductivity of oPBI-TAIC(5%)-SHBPBI(50%) at 0 RH remained 97.1% after washing with water for 96 h, indicating low leaching of the soluble proton conductor SHBPBI. The composite membranes exhibited potential application in HTPEM fuel cells and direct methanol fuel cells (DMFCs).

Intratumoral delivery of IL-12 and IL-27 mRNA using lipid nanoparticles for cancer immunotherapy.

Cytokines are important immunotherapeutics with approved drugs for the treatment of human cancers. However, systemic administration of cytokines often fails to achieve adequate concentrations to immune cells in tumors due to dose-limiting toxicity. Thus, developing localized therapy that directly delivers immune-stimulatory cytokines to tumors may improve the therapeutic efficacy. In this study, we generated novel lipid nanoparticles (LNPs) encapsulated with mRNAs encoding cytokines including IL-12, IL-27 and GM-CSF, and tested their anti-tumor activity. We first synthesized ionizable lipid materials containing di-amino groups with various head groups (DALs). The novel DAL4-LNP effectively delivered different mRNAs in vitro to tumor cells and in vivo to tumors. Intratumoral injection of DAL4-LNP loaded with IL-12 mRNA was most potent in inhibiting B16F10 melanoma tumor growth compared to IL-27 or GM-CSF mRNAs in monotherapy. Furthermore, intratumoral injection of dual DAL4-LNP-IL-12 mRNA and IL-27 mRNA showed a synergistic effect in suppressing tumor growth without causing systematic toxicity. Most importantly, intratumoral delivery of IL-12 and IL-27 mRNAs induced robust infiltration of immune effector cells, including IFN-γ and TNF-α producing NK and CD8+ T cells into tumors. Thus, intratumoral administration of DAL-LNP loaded with IL-12 and IL-27 mRNA provides a new treatment strategy for cancer.

In situ Polymerized FDU‐12/Poly(methyl methacrylate) and FDU‐12/polyamide 6 Nanocomposites for Cd2+ Adsorption

AbstractLarge‐pore mesoporous silica FDU‐12 was synthesized and functionalized with silane coupling agents bearing methacrylate and diamino groups. Diamino‐functionalized FDU‐12/polyamide 6 and methacrylate‐functionalized FDU‐12/poly(methyl methacrylate) nanocomposites were prepared via in situ polymerization approach. These two synthesized nanocomposites were used as potential adsorbents for the removal of Cd2+ cations from aqueous media. The impact of different adsorption factors affecting the adsorption process was investigated, and isotherm and kinetic studies were conducted to gain a better understanding of adsorption mechanisms involved in the removal process of Cd2+ by the adsorbents. Experimental and computational results demonstrated that the adsorbents have acceptable performance for Cd2+ uptake.

Molecular dynamics simulation of novel diamino-functionalized hollow mesosilica spheres for adsorption of dyes from synthetic wastewater

We studied the facile synthesis, design, simulation, and modeling of novel diamino-functionalized hollow mesosilica spheres (DAF-HMSS) structures to remove Neutral Red (NR) and Crystal Violet (CV) from aqueous media. The synthesized sample was characterized by FESEM, TEM, LXRD, BET-BJH, and FTIR techniques. The adsorption and removal mechanism of these hazardous dyes on DAF-HMSS in the presence of water molecules was studied using molecular dynamics simulation. The equilibrium adsorption capacities of DAF-HMSS were computed via the conductor-like screening models with segmented activity coefficients known as COSMO-SAC. Simulation results of optimization by DMol3 showed that adsorption of CV dye by diamino groups of DAF-HMSS is more active in comparison with NR dye. Reactivity of molecules, chemical hardness (η), global softness, and electrophilicity index (ω) of compounds were assessed using the HOMO–LUMO gap. The Sigma profiles of DAF-HMSS with dyes showed that mesoporous adsorption of CV was more than NR while HOMO–LUMO energy gap of CV dye was less than NR. So, the chemical reactivity, chemical softness, and polarizability of CV dye were more than that of water and NR. Meanwhile, the kinetic stability of NR was more than CV dye. Besides, results of electrophilicity index (ω) exhibited high electrophilicity index of CV dye which indicates high toxicity of this dye.

Catalytic Lewis and Brønsted acid syn-diastereoselective benzylic substitutions of α-hydroxy-β-nitro- and α-hydroxy-β-azido-alkyl arenes

A series of alkyl and alkenyl p-methoxy arenes containing α,β-disubstituted diamino and amino alcohol groups were synthesized from β-nitro and β-azido benzylic alcohols in the presence of AuCl3 as catalyst. The formation of predominantly syn-disubstituted products were rationalized on the basis of mechanistic considerations and transition state models relying on A1,3-allylic strain. The products could have utility in the design of medicinally relevant compounds and as chiral ligands for asymmetric catalysis. A new synthesis of (+)-sertraline (Zoloft) was achieved.

An indole-based smart aerogel for simultaneous visual detection and removal of trinitrotoluene in water via synergistic effect of dipole-π and donor-acceptor interactions

In this study, an indole-based aerogel, 4-AING, was successfully constructed and used in simultaneous visual detection and removal of TNT in aqueous system. The diamino groups in 4-AING endowed it great abilities of recognition and adsorption of TNT through point-to-point electron donor-acceptor (D-A) interaction. On the other hand, by the help of the adjacent indole groups, the detection and adsorption process could be facilitated and promoted via face-to-point dipole-π interaction. The maximum adsorption capacity was up to 168.6 mg g−1 according to the Langmuir model. Furthermore, the 4-AING could be effectively regenerated without significant deterioration in its adsorption performance over 7 consecutive cycles, demonstrating the good reusability of 4-AING. The prepared 4-AING was exhibited an obvious color change from light brown to dark brown in the presence of TNT, which was visualized through naked-eye. A smartphone was applied for the colorimetric quantify the adsorption capacity of TNT with linearity range of 42.8 to 156.0 mg g−1 with the limit of detection of 2.9 mg g−1. The excellent adsorption and detection performances in real TNT wastewaters further confirmed the practical application of 4-AING in real wastewater treatment. These results indicated that 4-AING can be used as a smart material in monitoring water quality and treating wastewater.

Diamine-functional bisphthalonitrile: Synthesis, characterization and its application in curing epoxy resin

A novel bisphthalonitrile containing diamino group (BhPN) was successfully synthesized and characterized by FT-IR and 1H NMR spectra. The BhPN monomer showed a self-promoted curing behavior and good processability confirmed by differential scanning analysis and rheological analysis, respectively, and its apparent activation energy was determined by the Kissinger’s method. Thermogravimetric analysis and dynamic mechanical analysis indicated that the temperatures of 10% weight loss and glass-transition of BhPN polymer were in the ranges of 480–506 °C and 307–403 °C, respectively, which were significantly dependent on the curing temperature. Furthermore, the BhPN monomer was used as a new curing agent of bisphenol-A diglycidyl ether (DGEBA) and the possible curing mechanism was proposed. The thermal stabilities and viscoelastic properties of epoxy resins cured with different curing agents including BhPN and 4,4′-diaminodiphenyl methane (DDM) were made a detailed comparison. As a result, the cured DGEBA/BhPN system showed higher char yield, glass-transition temperature, and elasticity modulus compared to the DGEBA/DDM system because of the additional polymerization of cyano groups.

A simple and efficient method for the synthesis of 5,6-dihydropyrazin-2(1H)-one O-(tert-butyl)oximes, quinoxalin-2(1H)-one O-(tert-butyl)oximes and its derivatives

A simple and efficient method was developed for the synthesis of 5,6-dihydropyrazin-2(1H)-one O-(tert-butyl)oximes, quinoxalin-2(1H)-one O-(tert-butyl)oximes and its derivatives from N-tert-butoxy acyl imidoyl bromide and diamines. Twenty three novel compounds were readily synthesized using this procedure in excellent yields. The products possessed Z-stereochemistry with regard to the CN double bond. In these reactions, the amino group first attacked an imidoyl carbon of the N-tert-butoxy acyl imidoyl bromide in order to obtain the Z-intermediate; then another amino group attacked the carbonyl carbon of the intermediate. The rate of intramolecular cyclization of the intermediate was dependent on the position of the diamino groups.

Aromaticity of benzene derivatives: an exploration of the Cambridge Structural Database.

The harmonic oscillator model of aromaticity (HOMA) index, one of the most popular aromaticity indices for solid-state benzene rings in the Cambridge Structural Database (CSD), has been analyzed. The histograms of HOMA for benzene, for benzene derivatives with one formyl, nitro, amino or hydroxy group as well as the histograms for the derivatives with two formyl, nitro, amino or hydroxy groups in ortho, meta and para positions were investigated. The majority of the substituted benzene derivatives in the CSD are characterized by a high value of HOMA, indicating fully aromatic character; however, the distribution of the HOMA value from 1 to about 0 indicates decreasing aromaticity down to non-aromatic character. Among the benzene derivatives investigated, a significant decrease in aromaticity can be related to compounds with diamino and dinitro groups in the meta position.

High temperature proton exchange membranes based on cerium sulfophenyl phosphate doped polybenzimidazole by end-group protection and hot-pressing method

Cerium sulfophenyl phosphate (CeSPP) doped polybenzimidazole (PBI) composite membranes were prepared by hot-pressing method as promising candidates for high temperature proton exchange membranes. In order to improve the oxidative stability of the composite membrane (PBI/CeSPP), the active vicinal diamino groups on polymer ends were protected by transformation into benzimidazolones. It was found that the membranes prepared from end-group protected PBI (e-PBI) had an evidently enhanced oxidative stability in comparison with the membrane made from unprotected PBI (u-PBI). CeSPP was found to be well dispersed in the polymer matrix due to its organic-inorganic nature and the strong ionic/hydrogen bonding between PBI and it. The composite membrane exhibited good mechanical strength and thermal stability up to 200 °C. The temperature and relative humidity dependence of the proton conductivity was investigated. The proton conductivity of e-PBI/CeSPP (25 wt%) at 180 °C reached 0.11, 0.039 and 0.0024 S cm−1 at 100%, 50% and 0 relative humidity, respectively.

Preparation of amino-Fe(III) functionalized mesoporous silica for synergistic adsorption of tetracycline and copper

Finding effective methods for simultaneous removal of antibiotics and heavy metals has attracted increasing concern since both of them are frequently detected in aquatic environments. In this study, a novel mesoporous silica adsorbent (Fe-N,N-SBA15) contained dual-functional groups was synthesized by first grafting di-amino groups on SBA15, and then coordinating Fe(III) onto the adsorbent. The adsorbent was then used in the synchronous elimination of tetracycline (TC) and Cu(II) from water, which was deeply studied by solution pH, kinetics, equilibriums in sole and binary systems. It was found that the adsorbent had high affinity for both TC and Cu(II) and synergistic effects on the adsorption were found. The solution pH remarkably affected the adsorption due to pH-dependent speciation of TC, Cu(II), TC–Cu(II) complex and the surface properties of the adsorbent. Increasing adsorption amount of TC and Cu(II) on the adsorbent could be attributed to the formation of complex TC–Cu(II) bridging or the stronger affinity of the adsorbent for the TC–Cu(II) complex than that for TC or Cu(II) separately. FT-IR and XPS studies revealed that Fe(III) and amino groups on the adsorbent were complexed with the amide of TC and Cu(II), respectively. The recyclabilities of the adsorbent were also evaluated and the Fe-N,N-SBA15 exhibited good reusability for TC and Cu(II) removal. This study shows guidelines and offers an innovative, effective method for the synergistic removal of antibiotics and heavy metals from aquatic environments.

Flame retardancy, mechanical, and thermal properties of waterborne polyurethane conjugated with a novel phosphorous-nitrogen intumescent flame retardant

A novel phosphorous-nitrogen intumescent flame retardant with reactive diamino groups, benzoguanamine spirocyclic pentaerythritol bisphosphonate (BSPB), was synthesized and used as a chain extender, and then a series of flame retardant waterborne polyurethanes (FRWPU) were prepared by covalently conjugating the BSPB into waterborne polyurethane (WPU) backbone. Their structures were characterized by Fourier transformed infrared spectrometry (FTIR), 1H and 31P nuclear magnetic resonances (NMR), respectively. Simultaneously, the flame retardancy and the thermal stability of FRWPU were systematically investigated by limiting oxygen index (LOI) test, UL-94 vertical burning test and thermogravimetric analysis (TGA). The results indicated that with the increase of BSPB content from 0 to 8 wt%, the LOI value of FRWPU increased from 18.6 to 27.3%, showing significant improvement by 8.7%. Compared with WPU, FRWPU showed decreased thermal stability but promoted char residue ratio. Conjugation of BSPB could obviously enhance the mechanical properties of FRWPU, the Young's modulus and tensile strength dramatically increased with the increase of BSPB. Investigation of char forming mechanism of BSPB through real time Fourier transform infrared spectra (RTFTIR) and scanning electronic microscopy (SEM) revealed that the polyphosphoric acid and phosphorus oxynitrides rich outer intumescent char layer could form protective shields to inhibit effectively internal polyurethane to heat and flame diffusion during contacting fire. POLYM. COMPOS., 2015. © 2015 Society of Plastics Engineers

Adsorption of Pb(II) ions in aqueous solutions by common reed ash-derived SBA-15 modified by amino-silanes

Amino, di-amino, and tri-amino groups functionalized mesoporous silica (N-SBA-15, 2 N-SBA-15, and 3 N-SBA-15) were synthesized using reed ash as silica source. Batch experiments were conducted to investigate the impact of contact time, adsorbent dosage, solution pH, temperature, and concentration of Pb(II) ions onto SBA-15, N-SBA-15, 2 N-SBA-15, and 3 N-SBA-15. The results revealed that the overall adsorption process well fitted the pseudo-second-order kinetic model. The maximum adsorption capacity of N-SBA-15, 2 N-SBA-15, and 3 N-SBA-15 for Pb(II) was 108.16, 102.77, and 93.65 mg/g at 298 K, respectively. The adsorption capacities increased with the increase in temperatures and with the decrease in soluble salt concentrations. Thermodynamics analysis showed that the adsorptions of Pb(II) were feasible, spontaneous, and exothermic in nature. The capacity of the modified SBA-15 did not lose significantly after six adsorption–desorption cycles. The Pb(II) adsorption process was dominated by chemical adsorption process. The results suggested that reed ash was an ideal silica source to prepare N-SBA-15, 2 N-SBA-15, and 3 N-SBA-15 for the removal of Pb(II) ions from aqueous solutions.

Mesopolymer modified with palladium phthalocyaninesulfonate as a versatile photocatalyst for phenol and bisphenol A degradation under visible light irradiation

A novel versatile photocatalyst, FDU-PdPcS, was prepared by immobilizing palladium phthalocyaninesulfonate (PdPcS) onto the FDU-15 mesopolymer via multi-step chemical modification processes involving chloromethylation of the FDU-15 mesopolymer first with chloromethyl methyl ether, a subsequent amination reaction with ethylenediamine, and finally modification with palladium phthalocyaninesulfonate via ionic interaction. The obtained FDU-PdPcS photocatalyst was characterized by the X-ray diffraction (XRD), UV-Vis spectrosopy and inductively coupled plasma (ICP) techniques. This photocatalyst not only affords a high dispersion of monomeric PdPcS molecules, which may further be stabilized by the π-electron of benzene rings of FDU-15, but also provides a number of diamino groups inside the mesopores, which could be advantageous for the photodegradation of phenolic pollutants. In photodegradation studies of phenolic pollutants, the FDU-PdPcS catalyst exhibited excellent visible light photocatalytic activity and reusability. The photodegradation products of phenol and bisphenol A were investigated by the gas chromatoghraphy-mass spectrometry (GC-MS) technique. The results showed that the photodegradation products were composed of carboxylic acids and CO2. Isopropanol, sodium azide and benzoquinone were used as hydroxyl radical (OH•), singlet oxygen (1O2) and superoxide radical (O2•–) scavengers, respectively. The results suggested that 1O2 and O2•– were the prominent active species during the photodegradation process. A possible mechanism for the photodegradation of phenol was also discussed.

Development and application of a ruthenium(II) complex-based photoluminescent and electrochemiluminescent dual-signaling probe for nitric oxide

A ruthenium(II) complex, [Ru(bpy)2(DA-phen)](PF6)2 (bpy: 2,2'-bipyridine; DA-phen: 5,6-diamino-1,10-phenanthroline), has been developed as a photoluminescent (PL) and electrochemiluminescent (ECL) dual-signaling probe for the highly sensitive and selective detection of nitric oxide (NO) in aqueous and biological samples. Due to the presence of electron transfer process from diamino group to the excited-state of the Ru(II) complex, the PL and ECL intensities of the probe are very weak. After the probe was reacted with NO in physiological pH aqueous media under aerobic conditions to afford its triazole derivative, [Ru(bpy)2(TA-phen)]2+ (TA-phen: 5,6-triazole-1,10-phenanthroline), the electron transfer process was inhibited, so that the PL and ECL efficiency of the Ru(II) complex was remarkably increased. The PL and ECL responses of the probe to NO in physiological pH media are highly sensitive with the detection limits at low micromolar concentration level, and highly specific without the interferences of other reactive oxygen/nitrogen species (ROS/RNS) and metal ions. Moreover, the probe has good cell-membrane permeability, and can be rapidly transferred into living cells for trapping the intracellular NO molecules. These features enabled the probe to be successfully used for the monitoring of the endogenous NO production in living biological cell and tissue samples with PL and ECL dual-modes.